Electricity: motive power systems – Positional servo systems – Pulse-width modulated power input to motor
Reexamination Certificate
2003-01-27
2004-06-08
Tapoloai, William E. (Department: 3744)
Electricity: motive power systems
Positional servo systems
Pulse-width modulated power input to motor
C318S811000
Reexamination Certificate
active
06747432
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates to a cooling fan motor drive apparatus for vehicles, which is made to drive vehicle cooling fan motors upon receipt of a power supply voltage through a power supply line.
2) Description of the Related Art
In a vehicle (such as a car), there is provided a cooling fan for cooling a radiator of an engine and condenser of an air conditioner, and so far, such a cooling fan has been rotationally driven by a motor (for example, DC motor).
FIG. 12
is an illustration of an electrical arrangement of a drive apparatus designed to drive two cooling fan motors in series/in parallel. In
FIG. 12
, a drive apparatus
1
employs a mainstream approach, made to drive cooling fan motors
2
and
3
in series or in parallel through the use of three relays according to cooling capability needed.
That is, a power supply line
4
is connected through an ignition switch (not shown) to a positive-side terminal of a battery, and one terminal of each of exciting coils
6
a
,
7
a
and
8
a
of the relays
6
,
7
and
8
is connected through a fuse
9
to the power supply line
4
. The other terminal of each of the exciting coils
7
a
and
8
a
is connected to the ground
12
through a water temperature switch
10
and an air conditioner high-pressure switch
11
placed in parallel with each other. Moreover, the other terminal of the exciting coil
6
a
is connected through an air conditioner amplifier
13
having an equivalent circuit illustrated and a switch
14
to the ground
12
, and further connected through the air conditioner
13
to the water temperature switch
10
and the air conditioner high-pressure switch
11
. To the air conditioner amplifier
13
, a battery voltage is supplied from the power supply line
4
through a fuse
15
, and the switch
14
takes a make-and-break action in conjunction with a magnet clutch (not shown).
Between a power supply line
16
connected directly to the positive-side terminal of the battery
5
and the ground
12
, there are formed a series circuit comprising a fuse
17
, a relay switch
6
b
, a cooling fan motor
2
and a relay switch
7
b
(at the on-condition of the normally-open contact) and a series circuit comprising a fuse
18
, a relay switch
8
b
and a cooling fan motor
3
. The normally-closed contact of the relay switch
7
b
is connected to the cooling fan motor
2
.
In this drive apparatus
1
, the operations of the cooling fan motors
2
and
3
in the states of the water temperature switch
10
, the air conditioner high-pressure switch
11
and the switch
14
(magnet clutch) are as shown in FIG.
13
. That is, the cooling fan motors
2
and
3
come to a stop when all the switches are in the off-condition, while they are drive in series when the switch is in the on-state and the air conditioner high-pressure switch
11
and the switch
14
are in the off-state, and driven in parallel when the water temperature switch
10
or the air conditioner high-pressure switch
11
is in the on-state.
The cooling fan motors
2
and
3
are located close to a condenser and radiator existing in the front part of a vehicle, and for simplifying the handling of a harness with respect to the cooling fan motors
2
and
3
and for reducing the loss in the harness, it is desirable that the drive apparatus is put in the vicinity of the cooling fan motors
2
and
3
. However, since the front part of a vehicle is exposed to bad environments because of being dashed with liquid or dust by the running of the vehicle, for installing the drive apparatus
1
therein, there is a need to place the relays
6
,
7
and
8
constituting the drive apparatus
1
in a dedicated relay box and reinforce the sealing structure. However, since the reinforcement of the sealing structure is costly, in the present circumstance the drive apparatus
1
is required to be located at a position (for example, the rear surface side of the engine room) remote from the cooling fan motors
2
and
3
and exposed to less liquid and dust.
In addition, since the drive apparatus
1
is composed of the fuses
9
,
15
,
17
,
18
and the relays
6
,
7
,
8
, for example, if the one cooling fan motor
2
is locked during the driving of the vehicle, the fuse
17
is fused so that the cooling fan motors
2
and
3
can be driven only when the fuse
17
is replaced with new one. Accordingly, once the motor lock occurs, difficulty is experienced in operating the cooling fan motors
2
and
3
even if it is released therefrom. Still additionally, in high-temperature and high-pressure conditions, only the other cooling fan motor
3
is driven to produce the lack of cooling capability, thus readily causing the overheating or the lowering of the performance of the air conditioner.
SUMMARY OF THE INVENTION
The present invention has been developed in consideration of the above-mentioned situations, and it is therefore an object of the invention to provide a cooling fan motor drive apparatus for use in a vehicle, capable of being placed close to vehicle cooling fan motors and, even if the cooling fan motor falls temporarily into an abnormal condition, capable of being restored to its normal condition after the recovery thereof.
For this purpose, according to the present invention, in a cooling fan motor drive apparatus for use in a vehicle which drives cooling fan motors upon receipt of a power supply voltage through a power supply line, first to fourth semiconductor switches are provided, and control means closes the second and fourth semiconductor switches to establish a current-carrying path extending from a first power supply line through the second semiconductor switch, a second vehicle cooling fan motor, the fourth semiconductor switch and a first vehicle cooling fan motor to a second power supply line so that the first and second vehicle cooling fan motors are driven in series, while the control means closes the first, second and third semiconductor switches to establish a current-carrying path extending from the first power supply line through the first semiconductor switch and the first vehicle cooling fan motor to the second power supply line and a current-carrying path extending from the first power supply line through the second semiconductor switch, the second vehicle cooling fan motor and the third semiconductor switch to the second power supply line so that the first and second vehicle cooling fan motors are driven in parallel.
As mentioned above, this drive apparatus is designed to switch the vehicle cooling fan motors between the serial and parallel operations and, hence, the semiconductor switches are easily configured into a sealed condition by means of resin molding or the like and the size reduction is further attainable in comparison with the conventional construction using relays. This enables the drive apparatus to be located in the vicinity of the cooling fan motors where the mounting space is difficult to secure and much dashed liquid and dust exist, which simplifies the handling of the harness with respect to the cooling fan motors and reduces the loss in the harness. Moreover, the employment of the semiconductor switches prevents damages and permits protection from overload, protection from overcurrent and protection from malfunction due to noises, and even if the cooling fan motor falls temporarily into an abnormal condition, it can be restored to a normal operation after the recovery from the abnormal condition.
In addition, in the drive apparatus according to the present invention, a reference current is set in accordance with a serial or parallel operation condition, and when a current flowing in the cooling fan motor exceeds the reference current, an output of a current-excess signal takes place. There is a situation that the operation of the cooling fan motor is required to be maintained to the utmost and it is undesirable that the operation thereof comes to a stop during the parallel operation which particularly requires a high cooling capability. Still additionally, considering the case t
Ali Mohammad M.
Denso Corporation
Posz & Bethards, PLC
Tapoloai William E.
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